A teaching union has condemned the makers of a documentary for secretly filming children swearing, fighting and downloading porn.

Pupils at six secondary schools in England were filmed by a teacher using cameras in a button and a briefcase.

The Channel Five programme Classroom Chaos has been criticised by the NUT for using "underhand methods" to film the children.

General Secretary Steve Sinnott said: "We condemn the methods used by the company.

"This is not an expose of the BNP or people abusing the elderly but of children who are learning."

He added: "Our research has already shown that lowlevel disruption is a major problem in our schools - we don't need cheap underhand methods to expose this."

The woman responsible for the filming, who is in her late 50s, is being identified only by a pseudonym, Sylvia Thomas.

She had reportedly returned to supply teaching after a 30-year-gap and taught at 18 schools in London and the north of England over a six-month period. She secretly filmed in six.

Ms Thomas said she saw chairs being smashed, pupils fighting in class and using mobile phones along with general rowdiness.

The individual schools, pupils and teachers involved are not identified in the programme which is due to be screened on Wednesday.

Five's senior programme controller, Chris Shaw, told the BBC: "I hope this film will open every parent's eyes to the chaos that reigns in many classrooms and makes meaningful teaching almost impossible."

Classroom Chaos will be broadcast on Five on Wednesday April 27 at 8pm.